Fabrication of nanostructured NiO/WO3 with graphitic carbon nitride for visible light driven photocatalytic hydroxylation of benzene and metronidazole degradation
In the present study we report a novel nanocatalyst prepared by the modification of g-C3N4 nanosheets with NiO/WO3 nanohybrid via simple ultra-sonication method where a novel method was employed for the synthesis of NiO/WO3. The morphology and optoelectronic properties of the synthesized heterojunction were thoroughly investigated using powder XRD, SEM, TEM, XPS, UV-DRS, PL and BET analysis. The photocatalytic efficiency of the synthesized catalysts were explored in C-H activation and degradation of a pharmaceutical waste namely metronidazole. The photocatalyst recorded distinctive activity in highly selective conversion of benzene to phenol with visible light irradiation by LED bulb. Degradation of metronidazole was carried out both; in presence of sunlight and LED light and monitored with UV-VIS spectroscopy. It was observed that, the degradation process was more efficient with irradiation by sunlight. The modified photocatalyst showed much higher efficiency compared to individual components of g-C3N4 and nanostructured NiO/WO3. This enhanced efficiency is attributed to larger surface area, lower band gap and delayed recombination of photogenarated charge carriers in the heterojunction. The catalyst was effectively recovered and reused for several times in both processes. The critical involvement of photoactive radicals in the degradation process was thoroughly investigated by trapping experiments using photoluminescence spectroscopy.